1. Field of the Invention
This invention relates to the interaction of transition metal complexes, more specifically, palladium complexes with H.sub.2 S. More particularly, this invention discloses a process for removing H.sub.2 S from a feedstock such as natural gas by means of a palladium metal-metal bonded dimer that abstracts the sulfur and generates hydrogen.
Field natural gas typically contains undesirable constituents such as H.sub.2 S which must be removed because of its corrosive and noxious nature. H.sub.2 S is now removed by treatment with aqueous ethanolamine in a countercurrent cycle followed by regeneration in a stripper column. Amines are often used and typical amines used are diisopropylamine or methyldiethanol amine. B,B'-hydroxyaminoethyl ether known as diglycolamine is also sometimes used.
The preferred alkanolamines typically have a hydroxyl group to lower the vapor pressure and to provide water solubility. The alkaline amine group absorbs acidic contaminant gases.
The alkanolamines, however, suffer several drawbacks--a problematic and costly one being the formation of irreversible reaction products with some contaminants such as COS and CS.sub.2. This results in an economic loss from loss of alkanolamine if these contaminants are present in the well. Other drawbacks of alkanolamines include relatively high corrosivity, vaporization losses due to their relatively high vapor pressure, and the need often to keep water content below 5% which necessitates high reboiler temperatures.
A sweetening process for soured natural gas, able to effectively remove H.sub.2 S but without many of the above attendant drawbacks, would be an advance in the art.
2. Description of Related Art
The palladium dimer complexes Pd.sub.2 Cl.sub.2 (.mu.-dppm).sub.2 have been reported by A. L. Balch, L. S. Benner, and M. M. Olmstead, Inorg. Chem., 1979, 18, 2996 and C. L. Lee, B. R. James, D. A. Nelson, and R. T. Hallen, Organometallics, 1984, 3, 1360.
The present invention discloses a new and useful process utilizing these complexes.